Speaker
Description
In Mediterranean forest regions such as the Pyrenees, Continuous Cover Forestry (CCF) is widely applied to maintain structural complexity and keep trees standing after harvesting. This approach often requires extraction systems that are flexible, minimally damaging, and capable of operating under variable terrains and stand structures. Among ground-based machines, the skidder is one of the most commonly used timber extraction tools due to its versatility, particularly when equipped with a winch for ground retrieval of stems from uneven terrain.
Traditionally, basic double-drum winch skidders (DDS) have been the dominant machinery in Mediterranean small-scale forests. However, more advanced configurations such as clambunk and crane skidders (CCS) are becoming increasingly adopted due to their higher load capacity and improved efficiency during loading and unloading operations. The literature on Mediterranean logging highlights significant differences in extraction productivity between configurations, and emphasizes the importance of machine type, skid trail conditions, and extraction distance on performance metrics in ground-based systems (e.g., winch vs grapple configurations).
The objective of this study was to compare the productivities of DDS and CCS machines under two forest management scenarios: a final felling in mountain pine stands and a close-to-nature thinning in Scots pine stands. In treatments where the CCS relied exclusively on the crane for loading and used the clambunk for transport, results showed a significant productivity advantage for CCS (6.4 m³/PMH) compared to DDS (4.6 m³/PMH). Conversely, when both skidders operated primarily with the winch — simulating conditions typical of selective or uneven-aged harvests — productivity differences were not statistically significant (3.88 vs. 3.83 m³/PMH for CCS and DDS, respectively).
These findings suggest that in operational contexts where crane-assisted loading is feasible and efficient, clambunk and crane skidders offer a clear productivity advantage over conventional winch-focused skidders. When the extraction context does not allow effective crane use (e.g., dense stands or complex ground conditions), machine productivity converges, reinforcing that operational conditions and silvicultural objectives influence the optimal machinery choice.
| Keywords | skidders, productivity, clumbunk, extracting |
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